Systems and methods for traffic-aware medium access selection

ABSTRACT

Diverse traffic types can be efficiently communicated in a simultaneous manner by dynamically selecting between contention-based and scheduling-based media access control (MAC) communication schemes. Such a mechanism may be particularly beneficial in networks having a contention-based access resources and scheduling based access resources. Contention-based resources and scheduling based resources may occur over a common period, and may be orthogonal in the frequency domain and/or in the code domain. The dynamic selection may be based on a traffic characteristic or a network characteristic, and may be performed on a packet-by-packet basis. The selection criteria may be updated dynamically to adapt to changing network conditions, and may be communicated to the various transmitters via control channels or higher layer signaling.

This patent application is a continuation of U.S. Non-Provisionalapplication Ser. No. 13/887,914, filed on May 6, 2013 and entitled“Systems and Methods for Traffic-Aware Medium Access Selection,” whichis hereby incorporated by reference herein as if reproduced in itsentirety.

TECHNICAL FIELD

The present invention relates generally to wireless communications, andin particular embodiments, to methods and systems for traffic-awaremedium access selection.

BACKGROUND

In conventional wireless access networks, mobile devices operate ineither a contention-based media access control (MAC) transmission modeor a contention-free MAC transmission mode. When operating in thecontention-based MAC transmission mode, the mobile device communicatesall traffic in accordance with a contention-based access technique.Likewise, when operating in the contention-free MAC transmission mode,the mobile device communicates all traffic using scheduling-basedaccess. Each MAC transmission mode has its advantages and disadvantages.For instance, scheduling-based access often provides higher quality ofservice (QoS) than contention-based access, while contention-basedaccess typically achieves lower latency times, particularly for smallpayload traffic.

As mobile device capability increases, it is likely that users may wantto communicate diverse traffic types simultaneously. For instance, auser may want to communicate a first traffic flow (e.g., a high QoStraffic flow) using scheduling-based access at the same time as a secondtraffic flow (e.g., latency-intolerant/low-capacity data flow) usingcontention-based access. Presently, the mobile station would need tocommunicate both traffic flows using the same MAC transmissiontechnique, depending on which MAC transmission mode the UE was operatingin. Hence, new mechanisms for efficiently communicating diverse traffictypes are desired.

SUMMARY OF THE INVENTION

Technical advantages are generally achieved, by embodiments of thisdisclosure which describe methods and systems for traffic-aware mediumaccess selection.

In accordance with an embodiment, a method for communicating data usingmultiple media access control (MAC) access techniques is provided. Inthis example, the method includes obtaining a first traffic flow and asecond traffic flow, and simultaneously communicating the first trafficflow and the second traffic flow over a network. The first traffic flowis communicated in accordance with a scheduling-based access MACcommunication scheme, and the second traffic flow is communicating inaccordance with a contention-based access MAC communication scheme. Anapparatus for performing this method is also provided.

In accordance with another embodiment, a method for communicatingcontrol information is provided. In this example, the method includesdetermining media access control (MAC) selection criteria in accordancewith conditions of a network, and communicating the MAC selectioncriteria to one or more mobile devices in the network. The MAC selectioncriteria specifies rules or parameters to be used by the mobile deviceswhen determining whether to communicate traffic using a contention-basedaccess MAC communication scheme or a scheduling-based access MACcommunication scheme. An apparatus for performing this method is alsoprovided.

In accordance with yet another embodiment, another method forcommunicating data using multiple media access control (MAC) accesstechniques is provided. In this example, the method includes obtaining aplurality of packets, determining, on a packet-by-packet basis, whetherto communicate the plurality of packets using contention-based orscheduling-based access, and simultaneously communicating a first packetand a second packet over a network. The first packet is communicated inaccordance with a scheduling-based access MAC communication scheme, andthe second packet is communicated in accordance with a contention-basedaccess MAC communication scheme.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates diagram of a wireless network for communicating data;

FIG. 2 illustrates a flowchart of an embodiment method for transmittingdata;

FIG. 3 illustrates a flowchart of an embodiment method for configuringMAC selection criteria;

FIG. 4 illustrates a block diagram of an embodiment device forcommunicating data;

FIG. 5 illustrates a flowchart of an embodiment method for selecting MACtransmission modes for communicating data;

FIG. 6 illustrates a protocol diagram of an embodiment communicationssequence for configuring MAC selection criteria;

FIG. 7 illustrates a diagram of embodiment communications channels;

FIG. 8 illustrates a diagram of embodiment communications channels; and

FIG. 9 illustrates a block diagram of an embodiment communicationsdevice.

Corresponding numerals and symbols in the different figures generallyrefer to corresponding parts unless otherwise indicated. The figures aredrawn to clearly illustrate the relevant aspects of the embodiments andare not necessarily drawn to scale.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of embodiments of this disclosure are discussed indetail below. It should be appreciated, however, that the conceptsdisclosed herein can be embodied in a wide variety of specific contexts,and that the specific embodiments discussed herein are merelyillustrative and do not serve to limit the scope of the claims. Further,it should be understood that various changes, substitutions andalterations can be made herein without departing from the spirit andscope of this disclosure as defined by the appended claims.

Disclosed herein are techniques for simultaneously communicating trafficflows using both scheduling-based access and contention-based access MACcommunication schemes. More specifically, aspects of this disclosureenable a mobile station to communicate a first traffic flow using ascheduling based access MAC communication scheme at the same time themobile station communicates a second traffic flow using acontention-based access MAC communication scheme. Simultaneoustransmission of both types is accomplished by simultaneously usingdifferent physical resources (for example: frequency, time, spreadingcode or any combination thereof). In embodiments, the mobile station maydynamically select between scheduling and contention based access forcommunicating a given traffic flow over the network. The mobile stationmay select the MAC communication scheme in accordance with a MACselection criteria, which may include a characteristic of the trafficflow and/or a characteristic of the network. For instance, the MACselection criteria may include a quality of service (QoS) requirement ofthe traffic flow (e.g., error rate, etc.), a latency requirement of thetraffic flow, an amount of data carried by the traffic flow, an amountof overhead associated with the data flow, a congestion level of acontention-based access channel (e.g., as indicated by a back-off timeor otherwise), a latency delay associated with a scheduling-based accesschannel, or any other factor. The selection criteria may be obtainedfrom a prior information of the mobile station, control informationcommunicated by a controller/base-station, or a combination thereof.

FIG. 1 illustrates a network 100 for communicating data. The network 100comprises an access point (AP) 110 having a coverage area 112, aplurality of user equipments (UEs) 120, and a backhaul network 130. TheAP no may comprise any component capable of providing wireless accessby, inter alia, establishing uplink (dashed line) and/or downlink(dotted line) connections with the UEs 120, such as a base station, anenhanced base station (eNB), a femtocell, and other wirelessly enableddevices. The UEs 120 may comprise any component capable of establishinga wireless connection with the AP 110. The backhaul network 130 may beany component or collection of components that allow data to beexchanged between the AP 110 and a remote end (not shown). In someembodiments, the network 100 may comprise various other wirelessdevices, such as relays, femtocells, etc.

Aspects of this disclosure provide a mechanism for dynamically selectinga contention-based or scheduling-based MAC communication scheme forcommunicating traffic over a network. In an embodiment, the wirelessaccess network may include a first MAC communication channel havingcontention-based access, as well as a second MAC communication channelhaving scheduling based access. The contention-based access channel mayoperate in accordance with the Institute of Electrical and ElectronicsEngineers (IEEE) 802.11ad (2012), which is incorporated by referenceherein as if reproduced in its entirety.

FIG. 2 illustrates an embodiment method 200 for transmitting data, asmay be performed by mobile station. As shown, the method 200 begins atstep 210, where the mobile station generates and/or receives a trafficflow. Thereafter, the method 200 proceeds to step 220, where the mobilestation selects either a contention-based access or scheduling-basedaccess MAC communication scheme for communicating the traffic flow overa network. In an embodiment, the mobile station's selection may be basedon MAC selection criteria. The MAC selection criteria may becommunicated by a base station or may be a priori information of themobile station. The MAC selection criteria may include a quality ofservice (QoS) requirement of the traffic flow (e.g., error rate, etc.),a latency requirement of the traffic flow, an amount of data carried bythe traffic flow, an amount of overhead associated with the data flow, acongestion level of a contention-based access channel (e.g., asindicated by a back-off time or otherwise), a latency delay associatedwith a scheduling-based access channel, or any other factor.

Subsequently, the method 200 may proceed to be step 230, where themobile station may communicate the traffic flow using the selected MACcommunication scheme. In instances where the mobile station selected ascheduling-based MAC communication scheme, the mobile station mayrequest uplink grant resources from the base station. In instances wherethe mobile station selects a contention-based MAC communication scheme,the mobile station may communicate the traffic flow without requestinguplink grant resources. For instance, the mobile station may use a“listen before talk” approach to communicating traffic over acontention-based communication channel.

In some embodiments, a communications controller or base station maycommunicate MAC selection criteria to the mobile station. Indeed, thebase station may dynamically select the MAC selection criteria inaccordance with conditions of the network. This may allow the accessnetwork to operate more efficiently and/or to adapt to changing networkconditions, e.g., traffic types, load conditions, etc. FIG. 3illustrates a method 300 for configuring MAC selection criteria, asmight be performed by a base station. As shown, the method 300 may beginat step 310, where the base station determines MAC selection criteria inaccordance with conditions of the network. Thereafter, the method 300may proceed to step 320, where the base station communicates the MACselection criteria to one or more mobile devices in the network. Forinstance, the base station may send a message to one or more mobilestations in the network. The message may be a broadcast message, amulticast message, or a unicast message. The message may be communicatedvia a control channel or, alternatively, through higher layer signaling,e.g., radio resource control (RRC) signaling.

FIG. 4 illustrates a device 400 for transmitting traffic flows. Asshown, the device 400 includes a packet scheduler 410, a MAC modeselector 420, a contention-based MAC communication module 430, ascheduling-based MAC communication module 440, and a hybrid automaticrepeat request (HARQ) module 450. The packet scheduler 410 may beconfigured to receive traffic flows. Traffic flows may include one ormore packets, and may be received concurrently with one another. In anembodiment, a traffic flow may include a single packet. The packetscheduler 410 may communicate traffic characteristics of the receivedtraffic flows to the MAC mode selector 420. The MAC mode selector 420may select a MAC mode for each of the traffic flows, and communicate theselected MAC modes to the packet scheduler 410.

The packet scheduler 410 may then forward traffic flows to either thecontention-based MAC communication module 430 or the scheduling-basedMAC communication module 440 depending on the select MAC mode for therespective traffic flows. The contention-based MAC communication module430 may communicate received flows in accordance with a contention-basedMAC communication technique, while the scheduling-based MACcommunication module 440 may communicate received flows in accordancewith a scheduling-based MAC communication technique. Accordingly, thetraffic flows may then be forwarded to the HARQ module 450, which mayprovide HARQ functionality for the device 400. For instance, the HARQmodule 450 may communicate acknowledgments and negative acknowledgmentsto confirm that transmissions were successfully received by the basestation, as well as re-communicate transmissions that were notsuccessfully received when necessary. In an embodiment, the MAC modeselector 420 is provided with a set of QoS characteristics by a basestation. In another embodiment, if the traffic flows to MAC modeselection is fairly static, (e.g., one or more traffic flows are mappedto contention-based MAC for a period of time), then traffic flows mayby-pass the packet scheduler altogether and be transmitted via thecontention-based MAC directly. In embodiments, the contention-based MACcommunication module 430 and the scheduling-based MAC communicationmodule 440 communicate packet flows simultaneously.

FIG. 5 illustrates a flowchart 500 for selecting a MAC transmissionmode, as may be performed by a mobile station in accordance withembodiments of this disclosure. As shown, the mobile station may firstmap each quality of service (QoS) queue to latency and reliabilitycriteria. Next, the mobile station may wait for a new packet to arriveor, alternatively, for a latency timer to expire. The mobile station maythen sort packets in accordance with their respective latencyrequirements, and identify packets whose maximum latency would beexceeded if transmitted using a scheduling-based access MACcommunication scheme. As discussed herein, packets whose maximum latencyrequirement would be exceeded if transmitted using scheduling-basedaccess are considered to be violating packets, while packets whosemaximum latency requirement would not be exceeded if transmitted usingscheduling-based access are considered to be non-violating packets. Themobile station transmits violating packets using a contention-basedaccess MAC communication scheme. The mobile station bundlesnon-violating packets, and then determines whether the bundle ofnon-violating packets exceeds a minimum scheduling-based packet size. Ifso, the bundle of non-violating packets is transmitting in accordancewith the scheduling-based access MAC communication scheme. If the bundleis too small for scheduling-based transmission, then the mobile stationdetermines whether the bundle of non-violating packets can betransmitted as contention based traffic. For instance, the bundle ofnon-violating packets may or may not have a traffic characteristics(e.g., QoS requirement, overhead, etc.) that prevents (or otherwisediscourages) contention-based transmission. When possible, the bundle ofnon-violating packets is transmitted using contention-based access. Ifthe bundle of non-violating packets cannot be transmitted usingcontention-based access, then the bundle is placed back into ascheduling-based transmission queue to be re-bundled with additionalnon-violating packets. Thereafter, the latency timer is reset.

FIG. 6 illustrates a protocol diagram 600 for communicating MACselection criteria, as might take place between a controller and UE. Asshown, the controller chooses MAC selection criteria beforecommunicating the MAC selection criteria to the UE. In some embodiments,the controller may send rules for selecting between contention-based andscheduling-based transmission during an initialization period, which mayallow the UE to provisionally classify packets, e.g., based on QoSbounds, header restriction, etc. Thereafter, the controller maycommunicate MAC selection parameters, which may allow the UE to performpacket classification. The messages sent from the controller to the UEmay be broadcast, multicast, or unicast messages. After classifying thepackets, the UE may perform data transmission.

Scheduling-based access resources and contention-based access resourcesmay be orthogonal in the frequency domain and/or in the code domain.FIG. 7 illustrates a transmission scheme 700 in which scheduling-basedaccess logical resources and contention-based access logical resourcesare positioned on different frequency resources during a common timeinterval/period. FIG. 8 illustrates a transmission scheme 800 in whichscheduling-based access logical resources and contention-based accesslogical resources are positioned on different spreading sequences/codesof a common time interval/period.

FIG. 9 illustrates a block diagram of an embodiment of a communicationsdevice 900, which may be equivalent to one or more devices (e.g., UEs,NBs, etc.) discussed above. The communications device 900 may include aprocessor 904, a memory 906, a cellular interface 910, a supplementalwireless interface 912, and a backhaul interface 914, which may (or maynot) be arranged as shown in FIG. 9. The processor 904 may be anycomponent capable of performing computations and/or other processingrelated tasks, and the memory 906 may be any component capable ofstoring programming and/or instructions for the processor 904. Thecellular interface 910 may be any component or collection of componentsthat allows the communications device 900 to communicate using acellular signal, and may be used to receive and/or transmit informationover a cellular connection of a cellular network. The supplementalwireless interface 912 may be any component or collection of componentsthat allows the communications device 900 to communicate via anon-cellular wireless protocol, such as a Wi-Fi or Bluetooth protocol,or a control protocol. The device 900 may use the cellular interface 910and/or the supplemental wireless interface 912 to communicate with anywirelessly enabled component, e.g., a base station, relay, mobiledevice, etc. The backhaul interface 914 may be any component orcollection of components that allows the communications device 900 tocommunicate via a supplemental protocol, including wire-line protocols.In embodiments, the supplemental interface 914 may allow the device 900to communicate with another component, such as a backhaul networkcomponent.

Although the description has been described in detail, it should beunderstood that various changes, substitutions and alterations can bemade without departing from the spirit and scope of this disclosure asdefined by the appended claims. Moreover, the scope of the disclosure isnot intended to be limited to the particular embodiments describedherein, as one of ordinary skill in the art will readily appreciate fromthis disclosure that processes, machines, manufacture, compositions ofmatter, means, methods, or steps, presently existing or later to bedeveloped, may perform substantially the same function or achievesubstantially the same result as the corresponding embodiments describedherein. Accordingly, the appended claims are intended to include withintheir scope such processes, machines, manufacture, compositions ofmatter, means, methods, or steps.

What is claimed:
 1. A method for communicating data using multipleaccess communication schemes over a network, the method comprising:receiving, by a mobile station, higher layer signaling controlinformation from a base station, the higher layer signaling controlinformation indicating selection criteria for a media access control(MAC) communication scheme, the MAC communication scheme comprising ascheduling based access communication scheme and a contention basedaccess communication scheme; and based on the received higher layersignaling control information, communicating, by the mobile station,first and second traffic flows over the network, wherein the firsttraffic flow is communicated using the scheduling based accesscommunication scheme, wherein the second traffic flow is communicatedusing the contention based access communication scheme, and whereinusing the scheduling based access communication scheme for the firsttraffic flow and the contention based access communication scheme forthe second traffic flow is in accordance with latency requirementsassociated with packets in at least one of the first traffic flow or thesecond traffic flow and a bundled size of the packets in at least one ofthe first traffic flow or the second traffic flow.
 2. The method ofclaim 1, wherein using the scheduling based access communication schemefor the first traffic flow and the contention based access communicationscheme for the second traffic flow depends on a Quality of Servicerequirement associated with at least one of the first and second trafficflows.
 3. The method of claim 1, wherein the second traffic flow istransmitted without a corresponding dynamic grant of uplink resources.4. The method of claim 1, wherein using the scheduling based accesscommunication scheme for the first traffic flow and the contention basedaccess communication scheme for the second traffic flow depends onconditions of the network.
 5. The method of claim 4, further comprisingreceiving information associated with the conditions of the network froma network entity.
 6. The method of claim 1 further comprising generatingat least one of the first and second traffic flows.
 7. The method ofclaim 1, wherein using the scheduling based access communication schemefor the first traffic flow and the contention based access communicationscheme for the second traffic flow depends on at least one of an amountof overhead associated with the first and second traffic flows or acongestion level of a contention based access channel for the contentionbased access communication scheme.
 8. The method of claim 1, thecommunicating further comprising: sorting, by the mobile station, newpackets based on latency requirements associated with the new packets;identifying, by the mobile station, a first subset of the new packetswhose associated latency requirements are not violated if transmittedusing the scheduling based access communication scheme; transmitting, bythe mobile station, the first subset of the new packets in the firsttraffic flow using the scheduling based access communication scheme if afirst bundled size of the first subset of the new packets is above aminimum size; identifying, by the mobile station, a second subset of thenew packets whose associated latency requirements are not violated iftransmitted using the scheduling based access communication scheme;transmitting, by the mobile station, the second subset of the newpackets in the second traffic flow using the contention based accesscommunication scheme if a second bundled size of the second subset ofthe new packets is below the minimum size; identifying, by the mobilestation, a third subset of the new packets whose associated latencyrequirements are violated if transmitted using the scheduling basedaccess communication scheme; and transmitting, by the mobile station,the third subset of the new packets in the second traffic flow using thecontention based access communication scheme.
 9. A method forcommunicating data, the method comprising: receiving, by a mobilestation, higher layer signaling control information from a base station,the higher layer signaling control information indicating selectioncriteria for a media access control (MAC) communication scheme, the MACcommunication scheme comprising a scheduling based access communicationscheme and a contention based access communication scheme; and based onthe received higher layer signaling control information, using thescheduling based access communication scheme for a first traffic flowand a contention based access communication scheme for a second trafficflow over a network in accordance with latency requirements associatedwith packets in at least one of the first traffic flow or the secondtraffic flow and a bundled size of the packets in at least one of thefirst traffic flow or the second traffic flow, the using comprising:transmitting, at the mobile station towards a network entity, a requestfor uplink grant resources; transmitting, at the mobile station, thefirst traffic flow towards the network entity in accordance with anuplink grant associated with the transmitted request; and transmitting,at the mobile station, the second traffic flow while transmitting thefirst traffic flow and without requesting a grant of uplink resources.10. The method of claim 9 wherein the second traffic flow is transmittedwithout a corresponding dynamic grant of the uplink grant resources. 11.The method of claim 9 wherein using the scheduling based accesscommunication scheme for the first traffic flow and the contention basedaccess communication scheme for the second traffic flow depends onconditions of the network.
 12. The method of claim 11, furthercomprising receiving information associated with the conditions of thenetwork from the network entity.
 13. The method of claim 9, whereinusing the scheduling based access communication scheme for the firsttraffic flow and the contention based access communication scheme forthe second traffic flow depends on a priori information stored in themobile station.
 14. The method of claim 9, wherein using the schedulingbased access communication scheme for the first traffic flow and thecontention based access communication scheme for the second traffic flowdepends on a Quality of Service requirement associated with at least oneof the first and second traffic flows.
 15. The method of claim 9 furtherincluding the step of generating at least one of the first and secondtraffic flows.
 16. A mobile station comprising: a processor; and acomputer readable storage medium storing programming for execution bythe processor, the programming including instructions for: receivinghigher layer signaling control information from a network entity and forcommunicating data over a network using a scheduling based accesscommunication scheme for a first traffic flow and a contention basedaccess communication scheme for a second traffic flow, the higher layersignaling control information indicating selection criteria for a mediaaccess control (MAC) communication scheme, the MAC communication schemecomprising a scheduling based access communication scheme and acontention based access communication scheme; based on the receivedhigher layer signaling control information, using the scheduling basedaccess communication scheme for the first traffic flow and a contentionbased access communication scheme for the second traffic flow over thenetwork in accordance with latency requirements associated with packetsin at least one of the first traffic flow or the second traffic flow anda bundled size of the packets in at least one of the first traffic flowor the second traffic flow, the using comprising: transmitting a requestfor uplink grant resources from the network entity; transmitting thefirst traffic flow towards the network entity in accordance with anuplink grant associated with the transmitted request; and transmittingthe second traffic flow while transmitting the first traffic flow andwithout requesting a grant of uplink resources.
 17. The mobile stationof claim 16 wherein the network entity is a base station.
 18. The mobilestation of claim 16, wherein the second traffic flow is transmittedwithout a corresponding dynamic grant of the uplink grant resources. 19.The mobile station of claim 16, wherein using the scheduling basedaccess communication scheme for the first traffic flow and thecontention based access communication scheme for the second traffic flowdepends on conditions of the network.
 20. The mobile station of claim19, wherein the programming further includes instructions to receiveinformation associated with conditions of the network from the networkentity.
 21. The mobile station of claim 16, wherein using the schedulingbased access communication scheme for the first traffic flow and thecontention based access communication scheme for the second traffic flowdepends on a priori information stored in the mobile station.
 22. Themobile station of claim 16, wherein using the scheduling based accesscommunication scheme for the first traffic flow and the contention basedaccess communication scheme for the second traffic flow depends on aQuality of Service requirement associated with at least one of the firstand second traffic flows.
 23. The mobile station of claim 16 wherein theprogramming further includes instructions to generate at least one ofthe first and second traffic flows.
 24. A mobile station comprising: aprocessor; and a computer readable storage medium storing programmingfor execution by the processor, the programming including instructionsfor: receiving higher layer signaling control information from a basestation, the higher layer signaling control information indicatingselection criteria for a media access control (MAC) communicationscheme, the MAC communication scheme comprising a scheduling basedaccess communication scheme and a contention based access communicationscheme; and based on the received higher layer signaling controlinformation, communicating first and second traffic flows over anetwork, wherein the first traffic flow is communicated using ascheduling based access communication scheme, wherein the second trafficflow is communicated using a contention based access communicationscheme, and wherein using the scheduling based access communicationscheme for the first traffic flow and the contention based accesscommunication scheme for the second traffic flow is in accordance withlatency requirements associated with packets in at least one of thefirst traffic flow or the second traffic flow and a bundled size of thepackets in at least one of the first traffic flow or the second trafficflow.
 25. The mobile station of claim 24, wherein using the schedulingbased access communication scheme for the first traffic flow and thecontention based access communication scheme for the second traffic flowdepends on a Quality of Service requirement associated with at least oneof the first and second traffic flows.
 26. The mobile station of claim24, wherein the second traffic flow is transmitted without acorresponding dynamic grant of uplink resources.
 27. The mobile stationof claim 24, wherein the scheduling based access communication schemefor the first traffic flow and the contention based access communicationscheme for the second traffic flow depends on conditions of the network.28. The mobile station of claim 27, wherein the instructions furthercomprise instructions for receiving information associated with theconditions of the network from a network entity.
 29. The mobile stationof claim 24 wherein the instructions further comprise instructions forgenerating at least one of the first and second traffic flows.
 30. Themobile station of claim 24 wherein using the scheduling based accesscommunication scheme for the first traffic flow and the contention basedaccess communication scheme for the second traffic flow depends on atleast one of an amount of overhead associated with the first and secondtraffic flows or a congestion level of a contention based access channelfor the contention based access communication scheme.